Signature device and signature method

ABSTRACT

A signature device including a storage unit configured to store moving image data, and a processor configured to extract original metadata from moving image data for the image data of each of a plurality of images forming the moving image data, the original metadata including location data of the image data and identification data of the moving image data, to encode the image data of each of the images into still image data in accordance with an image format, to write the still image data into a first area, to write the original metadata extracted by the extractor into a second area, the first area and the second area being included in a storage area of a still image data file in which the still image data is filed, and to generate summary data for the still image data file.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of theprior Japanese Patent Application No. 2011-61788, filed on Mar. 18,2011, the entire contents of which are incorporated herein by reference.

FIELD

The embodiment discussed herein is related to a signature device and asignature method which generates and verifies a signature.

BACKGROUND

In recent years, an observation camera is installed in a store, a busystreet or a condominium and a drive recorder is installed in a businessuse vehicle as usual, and moving image data is treated as evidence in anincreasing number of cases. Further, it is in the process of being acommon sense that a store records a conversation between a customer andan operator and keeps the record as evidence in order to deal with atrouble concerning trading on the phone or supporting business.

The store provides a videotape or an image or audio file as it is atpresent so as to give moving image data or voice as evidence. If,however, image or voice is stored increasingly in digital forms, it canbe easily altered or edited and thus will ask for third-partyauthentication such as a signature or timestamp so as to be treated asevidence. Services or products which record voice of a telephoneoperator with a timestamp are on sale in practice. It is expected thatthese kinds of technologies will be increasingly in demand.

Incidentally, a method for dividing contents in an electronic documentinto headings, calculating summary data of each of the headings, andadding an electronic signature to collection of the summary data of eachof the headings is used as a technology for detecting a third-party'salteration. The summary data mentioned here corresponds to hash datacalculated by the use of a cryptographic one-way hash function called amessage digest.

Further, a technology for providing an image file with an expanded areaand recording related data together with image data is disclosed withregard to image filing. Further, another technology for providing animage file with an expanded area and recording a plurality of copies orpartial copies of appended data corresponding to image data is disclosedwith regard to image filing (Japanese Laid-open Patent Publications No.2005-33503 and No. 2004-5934, e.g., discuss those technologies).

Further, a form of Internet service called cloud computing (called“cloud” hereafter) in which a user can use services provided by serverson the network without being aware of them has been mainstreamed inrecent years. Services for using the cloud so as to pile up and managedigitized moving images and voices in a center server in the cloud andto distribute content are being mainstreamed.

SUMMARY

According to an aspect of the invention, a signature device including astorage unit configured to store moving image data, and a processorconfigured to extract original metadata from moving image data for theimage data of each of a plurality of images forming the moving imagedata, the original metadata including location data of the image dataand identification data of the moving image data, to encode the imagedata of each of the images into still image data in accordance with animage format, to write the still image data into a first area, to writethe original metadata extracted by the extractor into a second area, thefirst area and the second area being included in a storage area of astill image data file in which the still image data is filed, and togenerate summary data for the still image data file.

The object and advantages of the invention will be realized and attainedby means of the elements and combinations particularly pointed out inthe claims. It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory and are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an explanatory diagram which depicts exemplary operations of asignature system of the embodiment in time of signature generation andin time of verification;

FIG. 2 is an explanatory diagram which depicts an exemplary device groupof the signature system;

FIG. 3 is a block diagram which depicts an exemplary function of anauthenticator device;

FIG. 4 is a block diagram which depicts an exemplary hardwareconstitution of the signature device;

FIG. 5 is a block diagram which depicts an exemplary function of thesignature device;

FIG. 6 is a block diagram which depicts exemplary functions of asignature generator, an image extractor and a signature verifier;

FIG. 7 is an explanatory diagram which depicts an exemplary operationaccording to a signature algorithm;

FIG. 8 is an explanatory diagram which depicts exemplary image types ofcompressed moving image data and their arrangement;

FIG. 9 illustrates an exemplary case in which P- and B-pictures ofcompressed moving image data are converted into independent images;

FIG. 10 is an explanatory diagram which exemplarily depicts what isstored in a user data list;

FIG. 11 is an explanatory diagram which depicts an exemplary method forgenerating a signature to be put to original moving image data;

FIG. 12 is an explanatory diagram which illustrates exemplary image datathat original metadata is added to;

FIG. 13 is an explanatory diagram which exemplarily depicts what isstored in an original moving image data registration list;

FIG. 14 is an explanatory diagram which depicts an exemplary method forgenerating a cut off still image data file;

FIG. 15A is an explanatory diagram which depicts an exemplary cut offstill image data file that original metadata and cut off metadata areadded to;

FIG. 15B is another explanatory diagram which depicts an exemplary cutoff still image data file that original metadata and cut off metadataare added to;

FIG. 16 is an explanatory diagram which depicts an exemplary method forverifying a signature put to a cut off still image data file;

FIG. 17 is an explanatory diagram which depicts an exemplary screen thata list of original moving image data is displayed on;

FIG. 18 is an explanatory diagram which depicts an exemplary screen thata cut off still image data file is made on;

FIG. 19 is an explanatory diagram which depicts an exemplary screen thata cut off still image data file to be verified is chosen on;

FIG. 20 is an explanatory diagram which depicts an exemplary screen thata result of verification of a cut off still image data file is displayedon;

FIG. 21 is an explanatory diagram which depicts an exemplary screen thatproperty data of a cut off still image data file is displayed on;

FIG. 22 is a flowchart which depicts an exemplary process forregistering a public key to be used for electronic signature;

FIG. 23 is a flowchart which depicts examples of a process for sendingand receiving data that an electronic signature is put to and averification process to be run by a receiver;

FIG. 24 is a flowchart which depicts an exemplary process for generatingoriginal moving image data;

FIG. 25A is a first page of a flowchart which depicts an exemplaryprocess for generating a signature to be put to original moving imagedata;

FIG. 25B is a second page of the flowchart which depicts the exemplaryprocess for generating the signature to be put to the original movingimage data;

FIG. 26 is a flowchart which depicts a process for generating anindependent frame;

FIG. 27A is a first page of a flowchart which depicts an exemplaryprocess for generating a cut off still image data file;

FIG. 27B is a second page of the flowchart which depicts the exemplaryprocess for generating the cut off still image data file;

FIG. 27C is a third page of the flowchart which depicts the exemplaryprocess for generating the cut off still image data file;

FIG. 27D is a fourth page of the flowchart which depicts the exemplaryprocess for generating the cut off still image data file;

FIG. 28 is a flowchart which depicts an exemplary process for verifyingsignature data of original moving image data;

FIG. 29A is a first page of a flowchart which depicts an exemplaryprocess for verifying a cut off still image data file; and

FIG. 29B is a second page of the flowchart which depicts the exemplaryprocess for verifying the cut off still image data file.

DESCRIPTION OF EMBODIMENTS

According to a cloud service included in ordinary technologies describedabove for providing third-party's authentication, however, moving imagedata or signature data is stored as the original in a center server. Asthe center server verifies part of the moving image data in conditionthat the large-sized moving image data and the signature data areintegrated and managed in a table, etc., there is a problem in that itis difficult to identify related data to be used for confirming theoriginal.

An object of the embodiment is to provide a signature device and asignature method which facilitates identification of related data to beused for confirming the original in order to reduce the above problemsthat the ordinary technologies have.

The embodiment of a disclosed signature device and a signature methodwill be explained in detail with reference to the drawings.

FIG. 1 is an explanatory diagram which depicts exemplary operations of asignature system 100 of the embodiment in time of signature generationand verification. The operation in time of signature generation will beexplained first. The signature system 100 including a signature deviceof the embodiment generates a piece of still image information (stillimage data) for every frame in a piece of moving image information(moving image data) 101 on the basis of the image information (imagedata) of each of the frames. In time of generation, the signature system100 writes metadata including an ID (IDentification) for identificationof the moving image data 101 and a frame number into an expanded areaaccording to an image format in a still image information file (stillimage data file) in which still image data is filed according to theimage format of the still image data. Incidentally, the metadata isadditional data related to the data to be generated itself.

Suppose that a JPEG (Joint Photographic Experts Group) format which isone of standard formats of compressed still images is used for the imageformat of the still image data file of the embodiment. Further, supposethat an MPEG (Moving Picture Experts Group) format which is one ofstandard formats of compressed moving images is used for moving imagedata.

After writing the metadata, the signature system 100 generates digestdata which summarizes the still image data file that the metadata iswritten into, and stores the digest data generated in order of the framenumbers in a storage area. After storing the digest data, the signaturesystem 100 makes a digest data group stored in order of the framenumbers an object to be signed 102, and provides the object to be signed102 with en electronic signature.

The signature system 100, e.g., encodes a frame 1 into still image data1. Then, the signature system 100 writes the metadata into an expandedarea of a still image data file 1 in which the still image data 1 isfiled. After writing the metadata, the signature system 100 generatesstill image data file 1 digest data which is digest data of the stillimage data file 1. The signature system 100 similarly generates stillimage data file 2 digest data and still image data file 3 digest data.After generating them, the signature system 100 provides the object tobe signed 102 filed in order of the frame numbers such as the stillimage data file 1 digest data, still image data file 2 digest data,still image data file 3 digest data and so on with an electronicsignature 103.

Further, the signature system 100 outputs a still image data file forwhich metadata is written into an expanded area of the still image datafile in order to open still image data to the public. The signaturesystem 100 opens the still image data file 2 as depicted in FIG. 1.

Then, the operation in time of verification will be explained. Thesignature system 100 extracts metadata filed in an expanded area from astill image data file to be verified. As the still image data file 2 issupposed to be the image to be verified in FIG. 1, the signature system100 extracts an ID and a frame number: 2 of the moving image data 101.

After extracting them, the signature system 100 searches a stored digestdata group of the object to be signed 102 for digest data correspondingto the data that the combination of the ID and the frame number of themoving image data 101 is extracted from. As the frame number: 2 issupposed, the still image data file 2 digest data is searched for inFIG. 1. If the still image data file 2 digest data agrees with thedigest data of the still image data file to be verified after thesearch, the signature system 100 can prove no alteration.

The signature system 100 signs the object to be signed including themetadata which facilitates identification of signature data forconfirming the original so that the signature data can be easilyidentified in time of signature verification as described above. Thesignature device of the embodiment will be explained hereafter by theuse of FIGS. 2 to 29B.

FIG. 2 is an explanatory diagram which depicts an exemplary device groupof the signature system 100. The signature system 100 includes anauthenticator device 201, an upload terminal 202, a playback/extractionterminal 203, a verification terminal 204 and a signature device 205.Those devices, the authenticator device 201 through the signature device205, are each connected to a network 206. Further, the upload terminal202 can communicate with a picture recorder terminal 207.

The authenticator device 201 is a server of an authenticator whichmanages electronic signature data. An electronic signature is formed bysummary data that an object to be signed is summarized into encryptedwith a secret key that a transmitter has. Then, the transmitter sendsthe electronic signature, the object to be signed and a certificate of apublic key to a receiver. The receiver checks validity of thecertificate of the public key, decodes the encrypted electronicsignature with the public key included in the certificate of the publickey, and compares the decoded electronic signature with summary dataobtained from the object to be signed. The authenticator device 201decides whether the electronic signature is sent from a right party ornot depending upon whether the comparison proves agreement or not. Theprocess will be described later in detail with reference to FIG. 23.

Further, the summary data described above is hash data calculated forthe object to be signed by the use of a cryptographic one-way hashfunction. The summary data is called a message digest as well, in orderto imply that the object to be signed can be compressed in size.Further, only the hash data generated by the use of the cryptographicone-way hash function is generated only from the object to be signed,and is characterized by a feature that original data will not berestored from the generated hash data.

Thus, the cryptographic one-way hash function is often used for dataencryption or electronic signature generation. The cryptographic one-wayhash function incorporates algorithms MD5 (Message Digest 5), SHA(Secure Hash Algorithm)-1 or SHA-256. Which algorithm is used for datato generate summary data (algorithm for generating hash data) is writtenin the certificate of the public key.

The upload terminal 202 obtains and stores streaming data recorded bythe picture recording terminal 207 (called original moving image data,hereafter), and runs a process for registering the original moving imagedata on the signature device 205.

The playback/extraction terminal 203 is a terminal that an extractoruses so as to play back and extract the original moving image data inthe signature device 205. The verification terminal 204 is a terminalthat a verifier uses so as to work the signature device 205 and verifypart of the original cut off the still image data file.

The signature device 205 is a center server in the signature system 100.The signature device 205 specifically stores and piles original movingimage data sent from the upload terminal 202, and runs a process forgenerating a signature. Further, the signature device 205 is instructedby the playback/extraction terminal 203 so as to run a process forplaying back and extracting the stored and piled moving image data.Further, the signature device 205 is instructed by the verificationterminal 204 so as to verify the original of the stored and piled movingimage data and to verify part of the original for a cut off the stillimage data file.

The network 206 may correspond to every type of communication networksuch as the Internet, an intranet, a wide area network, etc. The picturerecording terminal 207 is a terminal which films and records streamingdata to be made the original moving image data. A handheld video cameraor industrial surveillance camera, e.g., is employed as the picturerecording terminal 207. The picture recording terminal 207 cancommunicate with the upload terminal 202. Meanwhile, the picturerecording terminal 207 may exchange data with the upload terminal 202 bymeans of a removable recording media that the terminals 207 and 202 canbe equipped with, a USB (Universal Serial Bus) memory or anexclusive-use cable according to IEEE 1394, etc.

FIG. 3 is a block diagram which depicts an exemplary function of theauthenticator device 201. The authenticator device 201 includes a publickey DB (DataBase) 301, a certificate issuer 302, a certificate verifier303 and a communicator 304. A public key of the signature device 205 ispiled on the public key DB 301. The certificate issuer 302 issues acertificate of a public key as requested. The certificate verifier 303verifies a certificate of a public key. The communicator 304 isconnected to the network 206 and performs communication trough thenetwork 206.

(Hardware Constitution of Signature Device 205)

FIG. 4 is a block diagram which depicts an exemplary hardwareconstitution of the signature device 205. The signature device 205includes a CPU (Central Processing Unit) 401, a ROM (Read-Only Memory)402 and a RAM (Random Access Memory) 403 as depicted in FIG. 4. Thesignature device 205 further includes a magnetic disk drive 404, amagnetic disk 405, an optical disk drive 406 and an optical disk 407 asstorage devices. The signature device 205 further includes an I/F(Interface) 408. The respective portions are connected with one anotherthrough a bus 409.

The CPU 401 mentioned here controls the entire signature device 205. TheROM 402 stores therein programs including a boot program. The RAM 403 isused as a work area for the CPU 401. The magnetic disk drive 404controls operations to read and write data from and to the magnetic disk405 as controlled by the CPU 401. The magnetic disk 405 stores thereinwritten data as controlled by the magnetic disk drive 404.

The optical disk drive 406 controls operations to read and write datafrom and to the optical disk 407 as controlled by the CPU 401. Theoptical disk 407 stores therein written data as controlled by theoptical disk drive 406, or lets a computer read data stored in theoptical disk 407.

The I/F 408 is connected to the network such as a LAN (Local AreaNetwork), a WAN (Wide Area Network) or the Internet through acommunication line, and is connected to another device through thenetwork 206. Then, the I/F 408 controls the interface between thenetwork 206 and the inside of the signature device 205, and controlsdata input and data output from and to an external device. A modem orLAN adaptor, e.g., may be employed as the I/F 408.

Incidentally, the signature device 205 may include hardware componentsused as user interfaces such as a display monitor, a keyboard or a mouseif operated directly by a user.

FIG. 5 is a block diagram which depicts an exemplary function of thesignature device 205. The signature device 205 can access a moving imagemanagement DB 500 a, a moving image management TB 500 b, a keymanagement DB 501 a, a key management TB 501 b, a user management DB 502a, a user management TB 502 b and a signature device data management TB503. Further, the signature device 205 includes a signature generator504, an image extractor 505, a signature verifier 506 and a communicator507. The databases and tables, i.e., the moving image management DB 500a through the signature device data management TB 503 are each stored inthe storage devices such as the ROM 402, the RAM 403, the magnetic disk405, the optical disk 407, etc. Further, the functional portions, i.e.,the signature generator 504 through the communicator 507 each implementtheir function by means of the CPU 401 running programs stored in thestorage devices.

The moving image management DB 500 a is a database in which datareceived from the upload terminal 202 and data sent to theplayback/extraction terminal 203 are stored. The moving image managementTB 500 b is a table for managing data to control access to the movingimage management DB 500 a.

The key management DB 501 a is a database in which a certificate of apublic key issued by the authenticator device 201, a secret key forsignature corresponding to the certificate of the public key, and anencryption key for encrypting two kinds of metadata that the embodimentis related to which are original metadata and cut off metadata arestored. The key management TB 501 b is a table for managing data tocontrol access to the key management DB 501 a. Incidentally, themetadata and cut off metadata will be explained with reference to FIG.6.

The user management DB 502 a is a database for managing user data tocontrol user's access to the signature device 205. The user managementTB 502 b is a table for managing data to control access to the usermanagement DB 502 a. The signature device data management TB 503 is atable in which peculiar data to uniquely identify the signature device205 is stored.

The signature generator 504 has a function to put signature data tomoving image data. The image extractor 505 has a function to extract animage on a location to be extracted specified in the original movingimage data as a cut off still image data file as instructed by theplayback/extraction terminal 203. The signature verifier 506 receivesthe cut off still image data file from the verification terminal 204 andverifies part of the original. The communicator 507 performscommunication through the network 206.

(Functions of the Signature Generator 504, the Image Extractor 505 andthe signature verifier 506)

Then, exemplary functions of the signature generator 504, the imageextractor 505 and the signature verifier 506 will be explained. FIG. 6is a block diagram which depicts exemplary functions of the signaturegenerator 504, the image extractor 505 and the signature verifier 506.Incidentally, the signature generator 504 and the image extractor 505having some of the functions in common will be explained together.

Further, the signature generator 504 includes an input unit 601, amoving image decoder 602, a transfer unit 603, a converter 604 and astill image encoder 605. The signature generator 504 further includes anoriginal metadata extractor 606, an encryptor 607, a writer 608, adigest data generator 611 and an electronic signature generator 612.

The signature extractor 505 includes a specifying unit 609, a movingimage decoder 602, a transfer unit 603, a converter 604 and a stillimage encoder 605. The signature extractor 505 further includes anoriginal metadata extractor 606, an encryptor 607, a cut off metadatagenerator 610, a digest data generator 611, an electronic signaturegenerator 612 and an electronic signature verifier 613.

Further, the signature verifier 506 includes an input unit 621, anelectronic signature verifier 622, a metadata extractor 623, a decoder624, a searcher 625, a digest data generator 626, a decision unit 627and an output unit 628. Further, the signature generator 504, the imageextractor 505 and the signature verifier 506 can each access a storageunit 630.

This function to be a controller is specifically implemented, e.g., bythe CPU 401 running the programs stored in the ROM 402, the RAM 403, themagnetic disk 405, the optical disk 407 and so on depicted in FIG. 4.Meanwhile, the function may be implemented by another CPU running theprograms via the I/F 408. The function to be the controller isimplemented by the input unit 601 through the output unit 628.

The input unit 601 has a function to input data. The input unit 601inputs, e.g., original moving image data. Incidentally, inputted data isstored in storage areas such as the RAM 403, the magnetic disk 405, theoptical disk 407, etc.

The moving image decoder 602 has a function to analyze and obtain movingimage data for every one of plural images in the moving image data.Types of the image data includes a predictive frame which will not beplayed back independently and a moving image frame which can be playedback independently. The moving image decoder 602 analyzes and obtainspicture data for every frame, e.g., by means of an MPEG decoderaccording to an MPEG format. Incidentally, a predictive frame is a P- orB-picture according to MPEG, and a moving image frame which can beindependently played back is called an I-picture. The moving image datacomplies with various moving image formats including MPEG-1, MPEG-2,H264/AVC, etc. Incidentally, the decoded frames are each stored in astorage area in the RAM 403, the magnetic disk 405, the optical disk407, etc.

The transfer unit 603 has functions to transfer a predictive framehaving been inputted to the converter 604 and to transfer a first orsecond one of moving image frames having been inputted to the stillimage encoder 605. There are two types of the moving image frames whichare a first moving image frame having been present in the moving imagedata from the beginning and a second moving image frame that apredictive frame is converted into and is enabled to be played back bythe converter 604. If the moving image data is in an MPEG format, e.g.,the transfer unit 603 transfers a moving image frame enabled to beindependently played back that P- and B-pictures which are predictiveframes are converted into by the converter 604 to the still imageencoder 605. Incidentally, the transferred data is stored in the storagearea in the RAM 403, the magnetic disk 405, the optical disk 407, etc.

The converter 604 has a function to convert a predictive frame whichwill not be independently played back into a second moving image framewhich can be independently played back on the basis of a first movingimage frame which can be independently played back. The converter 604specifically converts, e.g., a P- and B-pictures which are predictiveframes into a moving image frame which can be played back on the basisof an I-picture which can be independently played back. Further, theconverter 604 converts a P-picture on the basis of a preceding I- orP-picture. Further, the converter 604 converts a B-picture on the basisof preceding and succeeding I- or P-pictures. Incidentally, theconverted frame is stored in the storage area in the RAM 403, themagnetic disk 405, the optical disk 407, etc.

The still image encoder 605 has a function to encode a first or secondmoving image frame into still image data according to an image format.The still image encoder 605 encodes, e.g., a moving image frame that P-and B-pictures have been converted into according to an MPEG format anda frame which is an I-picture into still image data according to theimage format. The image format except for a JPEG format is a JPEG 2000format, a PNG (Portable Network Graphic) format, etc. Incidentally, theencoded still image data is stored in the storage area in the RAM 403,the magnetic disk 405, the optical disk 407, etc.

The original metadata extractor 606 has a function to extract theoriginal metadata including location data of image data andidentification data of moving image data from the moving image data foreach of the plural images. Incidentally, the original metadata ismetadata for the original moving image data to be the original. Theoriginal metadata may include, e.g., generation time of the originalmoving image data, an ID of the signature device 205 that the originalmoving image data is registered in and so on in addition to locationdata of the image data and the identification data of the moving imagedata.

The original metadata extractor 606 extracts, e.g., original metadata,i.e., an original metadata ID “NA419” and location data “1” from theoriginal moving image data for the first image in the original movingimage data. Then, the original metadata extractor 606 extracts originalmetadata, i.e., the original metadata ID “NA419” and location data “2”from the original moving image data for the second image in the originalmoving image data. The original metadata extractor 606 extracts originalmetadata for all the images in the original moving image data in thisway. Incidentally, the extracted original metadata is stored in thestorage area in the RAM 403, the magnetic disk 405, the optical disk407, etc.

The encryptor 607 has a function to encrypt at least part of theoriginal metadata. The encryptor 607 encrypts, e.g., location data ofthe image data and identification data of the moving image data in theoriginal metadata. Further, the encryptor 607 may encrypt at least partof the cut off metadata. Incidentally, the encrypted original metadataor cut off metadata is stored in the storage area in the RAM 403, themagnetic disk 405, the optical disk 407, etc.

The writer 608 writes still image data for every image into a first areain an area that a still image data file into which image data is encodedaccording to the image format is stored in. Further, the writer 608 hasa function to write original metadata extracted by the original metadataextractor 606 into a second area.

Incidentally, the first area is an area in which a bit pattern ofencoded image data such as a DQT (Define Quantization Table) marker, aDHT (Define Huffman Table) marker, an SOF (Start of Frame) marker or anSOS (Start of Scan) marker, etc. is filed if the image is in a JPEGformat. The second area is an area which can be used for variouspurposes including APP0-APP15 markers, differently from the first area.Incidentally, the second area may be a tEXt chunk in which text data canbe embedded in case of another image format, e.g., PNG.

Further, one of the APP0-APP15 markers may have been used by anotherapplication program in some cases. If that is the case, the writer 608makes an unused one of the APP0-APP15 markers the second area and writesthe original metadata into the second area. The writer 608, e.g., filesthe image data and the original metadata into the first area and thesecond area, respectively, in order to encode the moving image frame bymeans of the still image encoder 605.

Further, the writer 608 may write cut off metadata generated by the cutoff metadata generator 610 into a third area in a still image data filein which still image data corresponding to location data specified bythe specifying unit 609 is filed. The still image data file in whichstill image data corresponding to the location data specified by thespecifying unit 609 is filed is a cut off still image data file.Incidentally, the third area is an area in the APP0-APP15 markers exceptwhere the original metadata is filed, e.g., in case of a JPEG format.

Further, the writer 608 may write summary data of a combination of thecut off still image data file and property data of its own into a fourtharea in the cut off still image data file. The fourth area is an area inthe APP0-APP15 markers except where the original metadata or the cut offmetadata is filed, e.g., in case of a JPEG format. Further, if the cutoff metadata is filed in the APP2 marker, an area indicated by the APP2marker may include both the third area in which the cut off metadata isfiled and the fourth area. Incidentally, the cut off still image datafile that the summary data has been written into is stored in thestorage area in the RAM 403, the magnetic disk 405, the optical disk407, etc.

The specifying unit 609 has a function to specify location data of imagedata on the basis of location data of one of plural images specified bya user to whom identification data is set. The specifying unit 609specifies, e.g., a frame number: 12355 which is location data of imagedata extracted by an extractor whom the signature device 205 logged in.Incidentally, the specified location data is stored in the storage areain the RAM 403, the magnetic disk 405, the optical disk 407, etc.

The cut off metadata generator 610 has a function to generate cut offmetadata including time when the specifying unit 609 specified thelocation data and identification data of a user who specified thelocation data by means of the specifying unit 609. The cut off metadatais metadata related to a cut off operation having been done. The cut offmetadata generator 610 generates cut off metadata including, e.g.,specified time “15A3:32 (HH:MM:SS), Aug. 13, 2010” and an ID of theextractor, “Suzuki Minoru: S15256”. Incidentally, the generated cut offmetadata is stored in the storage area in the RAM 403, the magnetic disk405, the optical disk 407, etc.

The digest data generator 611 generates summary data for a still imagedata file of every image after the writing operation done by the writer608. The digest data generator 611 generates, e.g., digest data for astill image data file encoded according to a JPEG format that theoriginal metadata is filed in.

Further, the digest data generator 611 may generate summary data of acombination of a cut off still image data file and property data of itsown. Incidentally, the digest data generator 611 may employ an ID of thesignature device 205 or of a network card of the signature device forits own property data.

Further, how to combine the cut off still image data file with theproperty data of the signature device 205 may be such that, e.g., a bitpattern of the property data of the signature device 205 may be coupledeither before or after a bit pattern of the cut off still image datafile. The digest data generator 611 may calculate an exclusive logicalsum of the bit pattern of the cut off still image data file and the bitpattern of the property data of the signature device 205 in order tocombine them in a different way.

Further, the digest data generator 611 may generate new summary data fora combination of original metadata of a cut off still image data file,cut off metadata and property data of the signature device 205. How tocombine the original metadata of a cut off still image data file, thecut off metadata and the property data of the signature device 205 maybe such that, e.g., bit patterns of the original metadata, the cut offmetadata and the property data of the signature device 205 in the aboveorder or in different order. Incidentally, the generated digest data isstored in the storage area in the RAM 403, the magnetic disk 405, theoptical disk 407, etc.

The electronic signature generator 612 generates an electronic signaturefor digest data generated by the digest data generator 611 and made anobject to be signed. The object to be signed may include digest data ofentire moving image data apart from digest data of a still image datafile. The electronic signature generator 612 generates an electronicsignature, e.g., by encrypting a collection of digest data having nframes with a secret key. Incidentally, the generated electronicsignature is stored in the storage unit 630.

The electronic signature verifiers 613 and 622 each have a function toverify authenticity of an electronic signature. If the electronicsignature verifier 613 decodes an electronic signature stored in thestorage unit 630 with a public key and a result of decoding agrees withsummary data of an object to be electronically signed, specificallye.g., the electronic signature verifier 613 outputs a conclusion thatthe electronic signature is guaranteed to be authentic. Incidentally,the result of the verification is stored in the storage area in the RAM403, the magnetic disk 405, the optical disk 407, etc.

The input unit 621 has a function to input a still image data file to beverified. The input unit 621 inputs a still image data file accordingto, e.g., a JPEG format, etc. Incidentally, the inputted still imagedata file is stored in the storage area in the RAM 403, the magneticdisk 405, the optical disk 407, etc.

The metadata extractor 623 has a function to extract data filed in thesecond area in the still image data file to be verified inputted by theinput unit 621. The metadata extractor 623 detects markers in the stillimage data file to be verified if the still image data file to beverified is, e.g., in a JPEG format. Upon detecting a marker that theoriginal metadata or cut off metadata is filed on, the metadataextractor 623 extracts data filed in an area specified by the relevantmarker. Incidentally, the extracted data is stored in the storage areain the RAM 403, the magnetic disk 405, the optical disk 407, etc.Instead, a pointer indicating where the data is extracted and dataindicating an area length may be stored in the storage area.

The decoder 624 has a function to decode encrypted data of the originalmetadata. Further, the decoder 624 decodes encrypted data in the cut offmetadata. Incidentally, the decoded data is stored in the storage areain the RAM 403, the magnetic disk 405, the optical disk 407, etc.

The searcher 625 has a function to search a summary data group stored inthe storage unit 630 for summary data for which a combination ofidentification data of moving image data and location data of image datacorresponds to data extracted by an extractor. Suppose, e.g., that thereare two blocks of original moving image data stored in the storage unit630 and their IDs are “DA104” and “NA419” each. Further, suppose that asummary data group of frame numbers 1 through 40000 of original movingimage data having the identification data “DA104” is stored in thestorage unit 630, and so is a summary data group of frame numbers 1through 30000 of original moving image data having the identificationdata “NA419”. Further, suppose that data extracted by the metadataextractor 623 is of “NA419” and “12355”.

At this time, the searcher 625 searches the summary data group stored inthe storage unit 630 for a summary data of a frame number 12355 of theoriginal moving image data having the identification data “NA419” whichcorresponds to “NA419” and “12355”. Incidentally, a result of the searchis stored in the storage area in the RAM 403, the magnetic disk 405, theoptical disk 407, etc.

The digest data generator 626 has a function to generate summary datafor the still image data file to be verified inputted by the input unit621. Incidentally, the generated digest data is stored in the storagearea in the RAM 403, the magnetic disk 405, the optical disk 407, etc.

The decision unit 627 has a function to decide whether the summary datasearched for by the searcher agrees with the summary data generated bythe digest data generator 626. Incidentally, a result of the decision isstored in the storage area in the RAM 403, the magnetic disk 405, theoptical disk 407, etc.

The output unit 628 outputs the result of the decision made by thedecision unit 627, e.g., to a device from which the still image datafile was inputted by the input unit 621.

The storage unit 630 stores therein moving image data. Further, thestorage unit 630 stores therein summary data of each of still image datafiles each including a first area and a second area. Still image dataencoded from image data is filed in the first area. Location data inmoving image data and identification data of the moving image data arestored in the second area. Incidentally, the storage unit 630 storestherein summary data of each the still image data files in connectionwith location data of each of images in the moving image data.

The storage unit 630 specifically stores therein the original movingimage data having the ID “NA419”. Further, the storage unit 630 storestherein digest data H1 and H2 through Hn for still image data a stillimage data that image data of the frame number 1 in the original movingdata is encoded into and a still image data file including “NA419” andthe frame number 1. Further, the digest data H1 and H2 through Hn isstored in connection with location data of each of the images in themoving image data. The digest data H1 and H2 through Hn may bespecifically stored in the above order in the storage unit 630. Apointer group indicating the digest data H1 and H2 through Hn may bestored in order of location data of each of the images in the movingimage data, instead. Incidentally, the moving image data and the summarydata are stored in the moving image management DB 500 a.

FIG. 7 is an explanatory diagram which depicts an exemplary operationaccording to a signature algorithm. The signature device dividesoriginal data 701 into partial data blocks, calculates a hash collectionof each of the partial data blocks and generates a hash data collection702. Then, the generated hash data collection 702 is made an object tobe electronically signed. The signature device electronically signs theobject to be signed. The signature device combines the hash datacollection 702 with the electronic signature to form signature data 703of the signature device.

The extractor device extracts partial data from the data that thesignature device has put the signature data to so as to generateextracted data 704. Then, the extractor device works similarly as thesignature device so as to generate a hash data collection 705. Theextractor device makes the hash data collection 705 an object to besigned, electronically signs the object to be signed and combines thehash data collection 705 with the electronic signature to form signaturedata 706 of the extractor device.

The verifier device verifies integrity of the hash data collection 702by means of the electronic signature of the signature device in thesignature data 703 of the signature device. The verifier devicesimilarly verifies integrity of the hash data collection 705 by means ofthe electronic signature of the extractor device in the signature data706 of the extractor device. Then, the verifier device generates a hashdata collection from disclosed partial data and verifies whether thegenerated hash data collection agrees with the hash data collection 705.The verifier device finally compares the hash data collections of thesignature device and the extractor device with each other so that it isknown that a range 708 of the hash data of the extractor device has beenextracted from a range 707 of the original data. If hash data of theextracted data 704 does not include hash data of the original data 701,it is known that the partial data has been altered.

FIG. 8 is an explanatory diagram which depicts exemplary image types ofcompressed moving image data and their arrangement. A frame includingcompressed moving image data can be roughly classified into a movingimage frame which can be independently played back and a predictiveframe having differential data with respect to the moving image frame.The predictive frame will not be independently played back.

According to the MPEG standard, a moving frame which can beindependently played back is called an I-picture, and a predictive frameis called a P- or B-picture. The I-picture keeps compressed image datacorresponding to one frame. Further, the I-picture includes an IDR(Instantaneous Decoder Refresh) picture added anew according to theH.264/AVC standard. The I- and IDR pictures will be explained simply asan I-picture hereafter. Features of the respective pictures will bedescribed later. The I-picture is a frame 801 in FIG. 8. The P-picturesare frames 804 and 805. The B-pictures are frames 802 and 803.

The P- and B-pictures are each called an inter-frame predictive image,as well. The P-picture incorporates predictive error data, i.e., adifference with respect to a most lately decoded I- or P-picture whichis made a reference image. The frame 804, e.g., is converted into aframe which can be independently played back with reference to an imagein the frame 801 which is an I-picture. The frame 805 is converted intoa frame which can be independently played back by the moving imagedecoder 602 with reference to an image in the frame 804 which is aP-picture.

The converter 604 carries out a forward prediction by referring to apast frame in order to convert a P-picture in this way. The frame whichis referred to is a latest I- or P-picture, and an earlier frame may bea reference frame according to H.264/AVC.

The B-picture incorporates predictive error data, i.e., differences withrespect to most lately decoded past and future I- or P-pictures whichare made reference images. The frame 802, e.g., is converted into aframe which can be independently played back with reference to images inthe frame 801 and 804 which are I- and P-pictures, respectively, and sois the frame 803.

The converter 604 carries out a bi-directional prediction by referringto past and future frames in order to convert a B-picture in this way.The frame which is referred to is a latest I- or P-picture for aB-picture similarly for a P-picture, and a frame one or more framesearlier or later may be a reference frame according to H.264/AVC.

Calculate differences between a P- or B-picture and frames located infront and back in this way so as to reduce redundancy in a direction oftime and to achieve a high data compression rate. Further, gatherseveral images as depicted in FIG. 8 to form data such that a pluralityof smallest units of moving image data called GOP (Group Of Pictures) iscollected for compressed moving image data. Let GOP=9, e.g., in FIG. 8.The GOP is a structure forming a unit which can be independently playedback so that moving image data can be played back or edited fromhalfway.

Further, a function of an IDR picture will be explained. According toH.264/AVC, as described earlier, a frame is referred to from a P- orB-picture beyond a latest I- or P-picture. It is thus unknown whether aplayback starts from an I-picture. An IDR picture alleviates thisproblem. Upon receiving an IDR picture, the moving image decoder 602clears a buffer that a reference frame is filed in, so as to guaranteethat the playback starts from the IDR picture. As the reference iscleared, no frame can be referred to from the P- or B-picture beyond theIDR picture.

FIG. 9 is an explanatory diagram which depicts an exemplary case inwhich P- and B-pictures of compressed moving image data are convertedinto independent images. To begin with, suppose that data is filed inorder of frames to be referred to in the moving image data asexplanatorily indicated with a reference numeral 901. The compressedmoving image data is analyzed by the moving image decoder 602 for everyframe, i.e., for each of frames 905, 906 and 907. A specific analyticalexample is given such that data in an MPEG format which has beenentropy-encoded according to DCT (Discrete Cosine Transform) is decodedaccording to inverse DCT and analyzed for every frame.

As exemplarily depicted in FIG. 9, the frames 905, 906 and 907 are I-,P- and B-pictures, respectively. Then, the frames 905-907 are arrangedin order of the frames 905, 907 and 906 by the moving image decoder 602so as to be in a chronological order as indicated with a referencenumeral 902.

Then, a process for converting the P- and B-pictures into independentimages will be described. An explanatory diagram indicted with areference numeral 903 depicts condition before a moving image frame isrestored. The frame 905 which is an I-picture holds the entire imagedata. The frames 906 and 907 which are P- and B-pictures, respectively,each hold predictive error data which is a difference of the image data.The converter 604 converts the frames 906 and 907 into frames 906′ and907′, respectively, which can be played back after a moving image frameis restored as indicated with a reference numeral 904.

Specifically, the converter 604 additionally writes the frame 906 whichis a difference on the frame 905 being a base so as to generate theframe 906′. Similarly, the converter 604 additionally writes the frame907 which is a difference on the frames 905 and 906 being bases so as togenerate the frame 907′

Further, the P- and B-pictures each have data of motion compensation inaddition to the predictive error data, and grasp to what extent theimage has moved in a particular range with respect to the I- andP-pictures being references. Incidentally, the moving image frame isrestored after the frames are rearranged to be obtained in chronologicalorder for convenience of explanation in FIG. 9. Instead, the frames maybe rearranged to be obtained in chronological order after the movingimage frame is restored.

Then, a flow of data processing in the signature system of theembodiment will be explained by the use of an exemplary operation and anexemplary data structure. Further, what is supposed for the signaturesystem 100 of the embodiment is defined before the flow of dataprocessing is specifically explained. Terminals which access thesignature system 100 of the embodiment are the upload terminal 202, theplayback/extraction terminal 203 and the verification terminal 204.Three operators who operate the upload terminal 202, theplayback/extraction terminal 203 and the verification terminal 204 are aproducer, an extractor and a verifier, respectively.

The producer manages and operates the picture recorder terminal 207 soas to register original image data. Then, the producer operates theupload terminal 202 so as to register the original image data in thesignature device 205. Specifically, if recording start and recordingstop buttons with which the picture recorder terminal 207 is equippedare pressed, the picture recorder terminal 207 accepts instructions tostart and stop recording pictures, respectively. Further, the extractoroperates the upload terminal 202 so as to perform communication with thesignature device 205, and to issue instructions to register the originalimage data recorded by the picture recorder terminal 207.

Further, the playback/extraction terminal 203 cuts off part of originalimage data stored and piled in the signature device 205, and asks thesignature device 205 to generate a cut off still image data file.Further, the verifier operates the verification terminal 204 so as toask the signature device 205 to verify a disclosed cut off still imagedata file. Incidentally, suppose that the playback/extraction terminal203 in the signature system 100 of the embodiment cuts off a data fileof a single still image in the original moving image data.

FIG. 10 is an explanatory diagram which exemplarily depicts what isstored in a user data list. FIG. 10 depicts a producer user data list1001, an extractor user data list 1002 and a verifier user data list1003 filed in the user management DB 502 a.

The producer user data list 1001 includes two fields which are producerID and password fields. Identification data for enabling the producer tobe uniquely identified is filed in the producer ID field. A password forallowing the producer to log in the signature system 100 is filed in thepassword field. In FIG. 10, e.g., “Kimura Ryuuichi: K19203” is filed inthe producer ID field, and an encrypted password is filed in thepassword field.

Similarly, the extractor user data list 1002 includes two fields whichare extractor ID and password fields. Identification data for enablingthe extractor to be uniquely identified is filed in the extractor IDfield. A password for allowing the extractor to log in the signaturesystem 100 is filed in the password field.

Further, the verifier user data list 1003 includes two fields which areverifier ID and password fields. Identification data for enabling theverifier to be uniquely identified is filed in the verifier ID field. Apassword for allowing the verifier to log in the signature system 100 isfiled in the password field.

The signature system 100 uploads and registers the original moving imagedata recorded by the picture recorder terminal 207 into the signaturedevice 205 as instructed by the producer having logged in, andguarantees content of the original moving image data by putting asignature by means of the signature device 205. Incidentally, as puttinga signature while being unaware which part of the original moving imagedata is extracted, the signature system 100 extracts every one of theI-, P- and B-pictures. Further, the signature system 100 may extractonly the I-picture carrying a piece of information which can beindependently displayed.

Further, the signature system 100 partially extracts a data file of asingle still image from the original moving image data that thesignature device 205 has put a signature to as instructed by theextractor having logged in, and discloses the extracted file to theverification terminal 204 as a cut off still image data file.

Then, the signature system 100 verifies whether the disclosed cut offstill image data file is guaranteed by the signature device 205 asinstructed by the verifier having logged in. The signature system 100verifies whether the disclosed cut off still image data file is part ofthe original moving image data that the signature device 205 has put asignature to, and verifies in addition whether the playback/extractionterminal 203 extracted the cut off still image data file after theextractor logged in. Incidentally, the signature device 205 traces theprocedure of electronic signature described above in order to processthe electronic signature.

FIG. 11 is an explanatory diagram which depicts an exemplary method forgenerating a signature to be put to original moving image data. Thesignature device 205 analyzes original moving image data 1101 which hasbeen inputted to the signature generator 504 for every frame by means ofthe moving image decoder 602, and arranges the analyzed frames inchronological order. Further, the signature device 205 stores theoriginal moving image data 1101 in the storage unit 630. Then, thesignature device 205 transfers each of the frames to the converter 604if the frame is a P- or B-picture, and to the still image encoder 605 ifthe frame is an I- or IDR picture.

The signature device 205 converts the frames transferred to theconverter 604 into moving image frames which can be independently playedback by means of the converter 604. The converted moving image framesare specifically moving image frames F2 and F3 through Fn. Further, theconversion method was earlier described with reference to FIG. 9.Further, the moving image frame which can be played back may be in adata format which is a same as that of an I- or IDR picture, or anuncompressed image format.

Then, the signature device 205 encodes the moving image frames which areI- and IDR-pictures transferred from the transfer unit 603 and themoving image frames converted by the converter 604 by means of the stillimage encoder 605, and generates still images. The still images arespecifically still images J21, J2 and 33 through Jn.

Then, the signature device 205 extracts original metadata 1102 by meansof the original metadata extractor 606. Incidentally, an example of theextracted original metadata 1102 will be specifically described laterwith reference to FIG. 12. Further, the signature device 205 encryptspart of the original metadata 1102 extracted for the still image 31 bymeans of the encryptor 607, and writes the encrypted part into the stillimage 31. Then, the signature device 205 encrypts part of the originalmetadata 1102 extracted for the still image J2, and writes the encryptedpart into the still image J2. The signature device 205 writes theextracted original metadata into each of the still images up to Jn.Incidentally, a method for writing the original metadata 1102 into thestill images will be described later with reference to FIG. 12.

After writing the original metadata 1102, the signature device 205generates digest data for each of the still images into which theoriginal metadata 1102 is written by means of the digest data generator611. The signature device 205 specifically generates digest data H1 andH2 through Hn. Further, the signature device 205 generates digest dataHA for the entire original moving image data 1101.

Upon finishing generating all the digest data, the signature device 205generates electronic signatures of the signature device 205 to be put tothe digest data HA of the original moving image data 1101 and acollection of digest data of all the pictures by means of the electronicsignature generator 612. The signature device 205 sets the collection ofthe digest data and the electronic signatures of the signature device205 generated for the collection together as signature data of theoriginal moving image data.

The signature device 205 can use a one-way hash function to generate thedigest data, and can use a public key cryptosystem RSA (Rivest ShamirAdleman) to generate the electronic signatures. The one-way hashfunction may incorporate algorithms called MD5, SHA-1 and SHA-256.According to SHA-256, e.g., digest data is generated in 256 bits (32bytes) per one message.

If moving image data is recorded in 30 [fps] (fps: frame Per Second) fornearly one hour, e.g., frames as many as 30[fps]×60[seconds]×60[minutes]=108000 are preserved. According to theSHA-256 algorithm, the digest data is as large as 108000frames×32[bytes]=nearly 3.5[Mbytes] in size. The digest data and thesignature generated according to the RSA cryptosystem form signaturedata as large as nearly 4[Mbytes] in size together, so that thesignature device 205 can achieve a guarantee of features of the originalby preserving data not so large in size as the moving image data. Thesignature device 205 generates a signature to be put to original imagedata according to the above operations. What is specifically processedin FIG. 11 will be described later with reference to FIGS. 24 and 25.

FIG. 12 is an explanatory diagram which depicts an exemplary still imagedata file that original metadata is added to. FIG. 12 depicts a state inwhich the original metadata 1102 is written into the still image datafile J1 depicted in FIG. 11. Suppose that the still image data file J1is in a JPEG format. Data in two bytes formed by 0xFF and successive onebyte is defined as a marker to give JPEG data and its structure adistinction in the JPEG format. A kind of marker “0xFFD8”, e.g.,indicates an SOI (Start Of Image) marker to indicate a start of the JPEGfile. A marker “0xFFD9” indicates an EOI (End Of Image) marker toindicate an end of the JPEG file.

Further, there are APP0 through APP15 markers which can be used forvarious purposes. The APP0 through APP15 markers are given values“0xEFEO” through “0xFFEF”. The APP1 marker is set as a location that theoriginal metadata 1102 is written into according to the embodiment. Thestill image J1 includes an SOI marker, JPEG data, an APP1 marker and anEOI marker.

The original metadata 1102 written into the APP1 marker includes sevenfields which are marker, data length, original moving image data ID,frame number, registration time, producer ID and signature device IDfields. In the marker field, “0xFFE1” which indicates APP1 is filed. Inthe data length field, the number of bytes from the data length field tothe signature device ID field is filed. In the original moving imagedata ID field, an ID which can make the original moving image data 1101uniquely identifiable is filed. In the frame number field, a framelocation of a still image to be an object is filed.

In the registration time field, time when the original moving image data1101 is registered is filed. Incidentally, the registration time fieldis obtained with reference to an internal clock in the signature device205. Incidentally, suppose that time is periodically calibrated on theinternal clock in the signature device 205 and thus causes not so mucherror. The embodiment allows incorrect registration time, though.

The producer ID is an ID of a manager of the picture recorder terminal207 who records the original moving image data 1101 by using the picturerecorder terminal 207 and in addition registers the original movingimage data 1101 in the signature device 205 by using the upload terminal202. The signature device ID is an ID which can make the signaturedevice 205 uniquely identifiable. Incidentally, the signature system 100may include a plurality of signature devices 205. In that case, an IDwhich makes each of the plural signature devices 205 uniquelyidentifiable is filed in the signature device ID field.

In FIG. 12, e.g., the original metadata 1102 related to the still imageJ1 is filed. The original metadata 1102 specifically indicates that theID of the original moving image data 1101 is “NA419”, that the stillimage J1 is of a first frame, and that the time of generation is“10:23:45 (HH:MM:SS), Aug. 11, 2010”. Further, the original metadata1102 indicates that the producer who produced the original moving imagedata 1101 is “Sato Taro: S20233” and that the ID of the signature device205 is “http://server1.fj.com”.

Further, the signature device 205 may run an encryption process by usingan encryption key filed in the key management DB 501 a in the signaturedevice 205 so as to avoid leakage or alteration of the original metadata1102. Incidentally, a range to be encrypted includes the original movingimage data ID field through the signature device ID field.

FIG. 13 is an explanatory diagram which exemplarily depicts what isstored in an original moving image data registration list 1301. Theoriginal moving image data registration list 1301 is filed in the movingimage management DB 500 a. The original moving image data registrationlist 1301 includes three fields which are original moving image data ID,registration time and producer ID fields. The original moving image dataID, registration time and producer ID depicted in FIG. 12 are filed inthe original moving image data ID, registration time and producer IDfields, respectively.

New entries are added to the original moving image data registrationlist 1301 each time new original moving image data is registered. InFIG. 13, e.g., entries “NA419”,“10:23:45 (HH:MM:SS), Aug. 11, 2010” and“Sato Taro: S20233” are in the original moving image data ID,registration time and producer ID fields, respectively.

FIG. 14 is an explanatory diagram which depicts an exemplary method forgenerating a cut off still image data file. The signature device 205checks whether the original moving image data 1101 is unaltered. Thesignature device 205 specifically verifies data of a signature put tothe original moving image data 1101 by means of the electronic signatureverifier 622. The signature device 205 takes a specific method such asto bring out the original moving image data 1101 stored in the storageunit 630 and verify the electronic signature added to the signaturedata.

If the verification is successful, the signature device 205 brings outthe digest data HA of the entire original moving image data 1101 filedin the signature data. The signature device 205 compares the digest dataHA with digest data for the entire original moving image data 1101generated by the digest data generator 611 after bringing out the digestdata HA, and checks whether the both digest data are the same.

The signature device 205 records digest data of the entire originalmoving image data 1101 in advance and uses the entire digest data forcomparison in this way in order to detect alteration in the moving imagedata 1101. The signature device 205 can thereby confirm the originalmore quickly than it does in a case where digest data of all the stillimages are recalculated for comparison.

Upon confirming the original, the signature device 205 is instructedwith regard to a cut off location. If a frame corresponding to the cutoff location is a P- or B-picture, the signature device 205 converts theframe into a moving image frame by means of the converter 604, andfurther encodes the moving image frame. Suppose, e.g., that thesignature device 205 is instructed to cut off a 12355th frame in FIG.14. At this time, the signature device 205 converts a B-picture of the12355th frame into a moving image frame F12355 by means of the converter604, and further encodes the moving image frame F12355 and generatesstill image data J12355 by means of the still image encoder 605.

After generating the still image data, the signature device 205 extractsthe original metadata 1102 by means of the original metadata extractor606. Then, the signature device 205 encrypts and writes part of thegenerated original metadata 1102 into the still image data J12355. Thestill image data J12355 that the original metadata 1102 is written intois made a cut off still image data file J12355.

Then, the signature device 205 generates cut off metadata 1401 by meansof the cut off metadata generator 610. Incidentally, a specific exampleof the generated cut off metadata 1401 will be described later withreference to FIGS. 15A and 15B. Then, the signature device 205 encryptspart of the generated original metadata 1102 by means of the encryptor607. After the encryption, the signature device 205 generates digestdata for a combination of the cut off still image data file J12355 andthe cut off metadata 1401 by means of the digest data generator 611.After the generation, the signature device 205 writes the generateddigest data into a cut off log list 1501 which will be described laterwith reference to FIG. 15, or into the cut off metadata 1401. Finally,the signature device 205 writes the cut off metadata 1401 into the cutoff still image data file J12355.

Then, two forms of the cut off still image data file to which theoriginal metadata and the cut off metadata are added will be explainedwith reference to FIGS. 15A and 15B. FIG. 15A illustrates a state inwhich the original metadata 1102 and the cut off metadata 1401 arewritten into the still image J12355 depicted in FIG. 14, and the cut offlog list 1501 is stored in the signature device 205. Further, FIG. 15Billustrates a state in which the cut off metadata 1401 that the digestdata for the combination of the original metadata 1102 and the cut offstill image data file is added to is written into the still image J12355depicted in FIG. 14.

FIG. 15A is an explanatory diagram which depicts an example of the stillimage data file that the original metadata and the cut off metadata areadded to. Incidentally, as the data to be filed in the original metadata1102 was explained with reference to FIG. 12, its explanation isomitted.

The cut off still image data file depicted in FIG. 15A will be explainedfirst. The still image data file J12355 includes an SOI marker, JPEGdata being still image data, an APP1 marker, an APP2 marker and an EOImarker. The cut off metadata 1401 is filed in the APP2 marker.

The cut off metadata 1401 written into the APP2 marker includes fourfields which are marker, data length, cut off time and extractor IDfields. In the marker field, “0xFFE2” which indicates APP2 is filed. Inthe data length field, the number of bytes from the data length field tothe extractor ID field is filed. In the cut off time field, time whenthe cut off still image is generated is filed. In the extractor field,an ID of the user who generated the cut off still image is filed.

Further, the cut off log list 1501 filed in the moving image managementDB 500 a is a list that an entry is added to each time a cut off stillimage data file is generated. The cut off log list 1501 includes fourfields which are original moving image data ID, cut off time, extractorID and digest data of the cut off still image data file fields. In theoriginal moving image data ID field, a same value as the value in theoriginal moving image data ID field of the original metadata 1102 isfiled. In the cut off time field, a same value as the cut off time ofthe cut off metadata 1401 is filed. In the extractor ID field, a samevalue as the value in the extractor ID field of the cut off metadata1401 is filed. In the digest data of the cut off still image data filefield, digest data generated from the cut off still image is filed.

Further, the signature device 205 may perform encryption by using anencryption key filed in the key management DB 501 a in the signaturedevice 205 so as to avoid leakage or alteration of the cut off metadata1401. Incidentally, a range to be encrypted includes the cut off timethrough extractor ID fields.

Further, a range covered by the digest data of the cut off still imagedata file is a digest range 1 which covers the entire still image J12355depicted in FIG. 15A. Further, the range covered by the digest data ofthe cut off still image data file may be a digest range 2 which coversthe entire still image J12355 depicted in FIG. 15A. The digest range 2specifically covers the original moving image data ID field in theoriginal metadata 1102 through the extractor ID field in the cut offmetadata 1401.

Why the range covered by the digest data is limited to the digest range2 is, at first, that authenticity can be confirmed with regard to thecut off still image data file excluding the cut off metadata 1401depending upon the signature data put to the original moving image data1101. Thus, it is enough for the digest data of the cut off still imagedata file to cover the cut off metadata 1401. If the digest range coversonly the cut off metadata 1401, however, the cut off metadata 1401 canbe exchanged for different cut off metadata 1401.

Thus, if the range covered by the digest data includes at least theoriginal moving image data ID field and the frame number field, digestdata which is peculiar to the cut off still image data file can begenerated in the digest range 2. Incidentally, a period of time for dataprocessing according to the one-way hash function which generates digestdata can be rendered shorter as an inputted byte pattern is shorter. Thesignature device 205 can thereby shorten a period of time for generatingdigest data by narrowing the range covered by the digest data whilekeeping the cut off still image data file including the cut off metadata1401 from being altered or exchanged by a third party.

Incidentally, cut off meta data 1401 related to the still image J12355having been cut off is filed as depicted in FIG. 15A. The cut offmetadata 1401 specifically indicates that the time when the still imagewas cut off is 15A3:32 (HH:MM:SS), Aug. 13, 2010, and that the ID of theextractor who cut off the still image is “Suzuki Minoru: S13256”.Further, it is indicated that the digest data field in the cut off stillimage data file in the cut off log list 1501 indicates “FD81920B2”.

FIG. 15B is an explanatory diagram which depicts another example of thecut off still image data file that the original metadata and the cut offmetadata are added to. Incidentally, differences from what is depictedin FIG. 15A will be explained with reference to FIG. 15B. The cut offmetadata 1401 includes the digest data field of the cut off still imagedata file in the cut off still image data file depicted in FIG. 15B. Aswhat is stored in the digest data field of the cut off still image datafile, digest data generated for a combination of the cut off still imagedata file and data peculiar to the signature device 205 is filed. As thedigest data of the cut off still image data file is opened in FIG. 15B,the signature device 205 can keep the digest data from being forged bycombining the digest range and the peculiar data that only the signaturedevice 205 knows so as to generate the digest data.

The signature device 205 can generate digest data for the digest rangeand the peculiar data within the signature device 205 in this way, so asto keep the cut off still image data file from being altered orexchanged by a third party. Incidentally, it is preferable for thepeculiar data of the signature device 205 to be filed in the signaturedevice data management TB 503 in advance in such a way that no thirdperson can peruse the peculiar data. Although the signature device IDcan be used for the peculiar data of the signature device 205, it ispreferable to have another ID as the signature device ID is opened asincluded in the original metadata 1102.

Further, the signature device 205 generates digest data excluding aportion of the digest data field in the cut off still image data filewith regard to the digest range 1 of the digest data in the cut offstill image data file. On the other hand, the signature device 205 mayfix the digest data field in the cut off still image data file in sizeand generate the digest data in which every bit in the digest data fieldis given a value 0.

FIG. 16 is an explanatory diagram which depicts an exemplary method forverifying a signature put to the cut off still image data file. To beginwith, the signature device 205 extracts the original metadata 1102 andthe cut off metadata 1401 from the cut off still image data file to beverified according to the JPEG format by means of the metadata extractor623. Incidentally, if some of the fields of the original metadata 1102and the cut off metadata 1401 are encrypted, the signature device 205decodes the encrypted fields by means of the decoder 624.

Then, the signature device 205 generates digest data from the originalmoving image data 1101 stored in the storage unit 630 by means of thedigest data generator 626. Then, the signature device 205 brings out andcompares the signature data of both the generated digest data and theoriginal moving image data 1101, and decides whether the both signaturedata agree with each other.

If the both signature data agree with each other, the signature device205 verifies part of the original of the cut off still image data file.The signature device 205 specifically generates digest data from the cutoff still image data file except for the cut off metadata 1401.Incidentally, the signature device 205 generates digest data for theoriginal metadata 1102 included in the digest data of the cut off stillimage data file being kept encrypted with an encryption key. Why thesignature device 205 generates the digest data in a state of beingencrypted is that digest data was generated in a state of beingencrypted when the signature put to the original moving image data 1101was generated. Thus, the signature device 205 processes verification ina state of being encrypted for checking whether data is altered in theverification process, as well.

Then, the signature device 205 searches and brings out the digest datafiled in the signature data of the original moving image data 1101 withrespect to the frame number filed in the original metadata 1102. In FIG.16, e.g., as the frame number equal to 12355 is recorded in the originalmetadata, the signature device 205 brings out the 12355th digest datafiled in the signature data of the original moving image data. Afterbringing out that, the signature device 205 compares the digest datagenerated by the electronic signature verifier 622 with the brought outdigest data and decides whether the both digest data agree with eachother.

If the both digest data agree with each other, the signature device 205checks whether the cut off metadata is unaltered. The signature device205 specifically generates digest data of the original metadata and thecut off still image data file including the cut off metadata.Incidentally, the signature device 205 generates the digest data byincluding the cut off metadata encrypted with an encryption key and thepeculiar data of the signature device 205. After generating the digestdata, the signature device 205 compares the generated digest data withthe digest data filed in the cut off metadata and decides whether theboth digest data agree with each other. If the both digest data agreewith each other, the signature device 205 notifies the verificationterminal 204 of success in the verification. Then, exemplary screensdisplayed on the playback/extraction terminal 203 and the verificationterminal 204 will be explained with reference to FIGS. 17-21.

FIG. 17 is an explanatory diagram which depicts an exemplary screen thata list of the original moving image data 1101 is displayed on. Theplayback/extraction terminal 203 can choose original moving image datato be cut off if a checkbox (CHECK) is pressed. If the extractor pressesan OK button (OKRUN), a request for a cut off process is sent to thesignature device 205.

FIG. 18 is an explanatory diagram which depicts an exemplary screen thata cut off still image data file is made on. If the extractor presses aplayback button (PREVIEW), the playback/extraction terminal 203 playsthe original moving image data back. The extractor looks at andspecifies a cut off location while the playback is going on, so as toenable the playback/extraction terminal 203 to perform a cut offoperation.

A specific method for the cut off operation is as follows. Shift apointer to a location where the cut off operation is done on a seekbar(SEEKBAR) and press a cut off button (EXTRACTSET) upon the pointerreaching the location where the cut off operation is done, so that theplayback/extraction terminal 203 sets the cut off location. The cut offlocation (CUTPOINT) is specified owing to the above operation. Press arun button (EXTRACTRUN) so that the playback/extraction terminal 203sends cut off location data to the signature device 205.

FIG. 19 is an explanatory diagram which depicts an exemplary screen thata cut off still image data file to be verified is chosen on. If theextractor presses a reference button (REFERENCE), theplayback/extraction terminal 203 displays a cut off still image datafile preserved in the playback/extraction terminal 203 on a filemanagement window. After the extractor chooses a cut off still imagedata file to be verified and presses a signature verification button(VERIFYRUN), the playback/extraction terminal 203 sends the chosen cutoff still image data file to the verification terminal 204.

FIG. 20 is an explanatory diagram which depicts an exemplary screen thata result of the verification of the cut off still image data file isdisplayed on. The verification terminal 204 can demonstrate to theverifier a result such that the cut off still image data file is thestill image data file formed by extracted part of the original movingimage data and is unaltered after the extraction by displaying a resultof the verification (VERIFY1). Further, the verification terminal 204can display the cut off location indicating which part of the originalmoving image data is extracted (VERIFY2). Further, press a certificatecheck button so that the verification terminal 204 can display theelectronic signature data of the original moving image data and who madethe original moving image data (VERIFY3).

Further, press a property data check button so that the verificationterminal 204 displays a result such that the original metadata 1102 andthe cut off metadata having been unaltered are verified (VERIFY4). Anexemplary screen that property data is displayed on will be describedlater with reference to FIG. 21.

FIG. 21 is an explanatory diagram which depicts an exemplary screen thatthe property data of the cut off still image data file is displayed on.Press the property data check button so that the verification terminal204 displays a screen for resultant signature verification of the cutoff still image data file. The verification terminal 204 specificallydisplays content of the original metadata 1102 and the cut off metadata1401. The verifier checks the screen for resultant signatureverification of the cut off still image data file in this way, so thatthe verifier can confirm that the original moving image data is made bythe signature device 205 and is unaltered.

The signature system 100 runs five processes for generating originalmoving image data, generating a signature, verifying signature data,generating a cut off still image data file and verifying the cut offstill image data file by using the devices and functions describedabove. The respective processes will be explained with reference toflowcharts depicted in FIGS. 22 to 29B. Further, a dashed arrowindicates data sending and receiving among the plural devices in each ofthe flowcharts.

In the process for generating original moving image data, the signaturesystem 100 runs a process for generating a signature to be put to theoriginal moving image data, and its breakdown includes processes fordecoding a moving image of the original moving image data, generating anindependent frame and generating an electronic signature. In the processfor verifying signature data of the original moving image data, thesignature system 100 runs a process for verifying an electronicsignature to be put to the original moving image data. In the processfor generating a cut off still image data file, the signature system 100runs a process for verifying a signature to be put to the originalmoving image data and generating an independent frame. In the processfor verifying a cut off still image data file, the signature system 100runs a process for verifying signature data of the original moving imagedata. Further, the processes for generating an electronic signature andverifying an electronic signature incorporate processes for sending andreceiving data that an electronic signature is put to and verifying areceiver device depicted in FIG. 23 to be run after a process forregistering a public key of an electronic signature in advance asdescribed later with reference to FIG. 22.

FIG. 22 is a flowchart which depicts an exemplary process forregistering a public key to be used for electronic signature. FIG. 22depicts a process in which a public key is registered in between thetransmitter and the authenticator device 201. The transmitter of theelectronic signature of the embodiment is the signature device 205.

To begin with, the transmitter generates a pair of keys (secret andpublic keys) (operation S2201). Then, the transmitter inputs requestdata for certificate issuance (operation S2202). The input data isrelated to the signature device 205. Upon finishing inputting therequest data for certificate issuance, the transmitter sends theinputted request data for certificate issuance and the public key to theauthenticator device 201 (operation S2203).

The authenticator device 201 receives the request data for certificateissuance and the public key on the communicator 304 (operation S2204).The certificate issuer 302 in the authenticator device 201 generates apublic key certificate including the public key (operation S2205), andpiles the generated public key certificate on the public key DB 301(operation S2206). Then, the certificate issuer 302 controls thecommunicator 304 so as to send the issued public key certificate to thetransmitter having sent the request data for certificate issuance viathe network 206 (operation S2207).

Upon receiving the public key certificate (operation S2208), thetransmitter piles the secret key generated by the operation 2201 and thepublic key certificate issued by the authenticator device 201 on thestorage device that the transmitter itself has (operation S2209), andfinishes the process. The signature device 205 holds the secret key andthe public key certificate in the key management DB 501 a used as astorage area.

FIG. 23 is a flowchart which depicts examples of a process for sendingand receiving data that an electronic signature is put to and averification process to be run by the receiver. FIG. 23 depicts theprocess for sending and receiving data that an electronic signature isput to between the transmitter and the receiver, and the process forverifying the electronic signature in between the receiver and theauthenticator device 201. The transmitter and the receiver of theembodiment are each the signature device 205.

To begin with, the transmitter encrypts summary data (hash data) whichis an object to be signed with the secret key stored in the storage area(operation S2301). Data generated through the encryption forms anelectronic signature. Then, the transmitter sends the object to besigned, the electronic signature and the public key certificatesimilarly stored in the storage area to the receiver (operation S2302).

The receiver receives the object to be signed, the electronic signatureand the public key certificate (operation S2303), and sends the publickey certificate to the authenticator device 201 (operation S2304) inorder to check the term of validity, data of losing validity, etc.Suppose that the authenticator device 201 of the embodiment supports aseries of functions to issue and verify a certificate. Then, theauthenticator device 201 receives the public key certificate (operationS2305), verifies validity (operation S2306) and sends a result of theverification to the receiver (operation S2307).

The receiver receives the result of the verification (operation S2308)and checks whether the result of the verification proves validity(operation S2309). If the result of the verification does not provevalidity (operation S2309: No), the receiver decides that no fact thatthe received object to be signed is unaltered can be proved (operationS2313) and finishes the process. If the result of the verificationproves validity (operation S2309: Yes), the receiver generates summarydata (hash data) of the received object to be signed (operation S2310),and further decodes the received electronic signature with the publickey (operation S2311). Then, the receiver checks whether the generatedsummary data of the object to be signed agrees with a value obtainedfrom the electronic signature decoded with the public key (operationS2312).

If they do not agree with each other (operation S2312: No), the receivershifts to an operation S2313 and finishes the process. If they agreewith each other (operation S2312: Yes), the receiver decides that thefact that the received object to be signed is unaltered can be proved(operation S2314), holds the object to be signed (operation S2315) andfinishes the process. Upon going through the operation S2313, thereceiver may run a notification process for indicating that theelectronic signature was not proven on the operation terminal of thereceiver, e.g., the playback/extraction terminal 203 or the verificationterminal 204.

FIG. 24 is a flowchart which depicts an exemplary process for generatingoriginal moving image data. The picture recorder terminal 207 generatesoriginal moving image data (operation S2401). The picture recorderterminal 207 decides whether the picture recorder terminal 207 hasaccepted a request for a close of recording after generating theoriginal moving image data (operation S2402). Upon accepting no requestfor a close of recording (operation S2402: No), the picture recorderterminal 207 shifts to the process of the operation S2401 and continuesgenerating the original moving image data. Upon accepting a request fora close of recording (operation S2402: Yes), the picture recorderterminal 207 sends the completely generated original moving image datato the upload terminal 202 (operation S2403) and finishes the processfor generating original moving image data.

The upload terminal 202 receives the original moving image data(operation S2404). The upload terminal 202 stores the received originalmoving image data in the upload terminal 202 (operation S2405), andsends a request to the signature device 205 for login of a producer(operation S2406). At this time, the upload terminal 202 accepts userdata such as an ID and a password of the producer as an input from theproducer included in data for logging the producer in on the signaturedevice 205. The upload terminal 202 sends the user data and the originalmoving image data with the login request to the signature device 205.Incidentally, the upload terminal 202 waits for a reply to come from thesignature device 205 after the login.

Upon receiving the request for login from the upload terminal 202, thesignature device 205 certifies the producer whose data is in the userdata (operation S2407). A specific method for certifying the producer isas follows. If the producer user data list 1001 includes a record whichagrees with the received user data, the signature device 205 certifiesthe producer who requested to log in as the right producer. Aftercertifying the producer, the signature device 205 decides whether thecertification resultantly indicates the right producer (operationS2408).

If the right producer is indicated (operation S2408: Yes), the signaturedevice 205 runs a process for generating a signature to be put to theoriginal moving image data (operation S2409). The process for generatinga signature to be put to the original moving image data will bedescribed later in detail with reference to FIG. 25. After running thatprocess, the signature device 205 files the original moving image dataand the signature data in the moving image management DB 500 a via themoving image management TB 500 b (operation S2410). After filing them,the signature device 205 sends a result of a registration process to theupload terminal 202 (operation S2411). Unless the right producer isindicated (operation S2408: No), the signature device 205 notifies theupload terminal 202 of an error (operation S2412).

Upon receiving what is sent from the signature device 205, the uploadterminal 202 decides whether what is received is a result of theregistration process (operation S2413). If it is a result of theregistration process (operation S2413: Yes), the upload terminal 202displays the result of the registration process (operation S2414) andfinishes the process for generating the original moving image data.Unless it is a result of the registration process (operation S2413: No),the upload terminal 202 displays the error notification (operationS2415) and finishes the process for generating the original moving imagedata.

FIGS. 25A and 25B are flowcharts which depict an exemplary process forgenerating a signature to be put to original moving image data. To beginwith, see the flowchart depicted in FIG. 25A. The signature device 205allocates a new original moving image data ID and shelters the ID into astorage area (operation S2501). After sheltering it, the signaturedevice 205 obtains registration time and shelters the registration timeinto the storage area (operation S2502). Then, the signature device 205sets the original moving image data ID, the registration time and theproducer ID as a new record in the original moving image dataregistration list 1301 (operation S2503).

After setting them, the signature device 205 obtains a signature deviceID and shelters the signature device ID into the storage area (operationS2504). After sheltering it, the signature device 205 runs a movingimage decoding process for decoding the original moving image data(operation S2505). Details of the moving image decoding process areindicated by the reference numerals 901 and 902 in FIG. 9 describedearlier. The signature device 205 specifically runs the decoding processin accordance with a format of the original moving image data, decideswhich one of the I-, P- and B-pictures the respective frames are, andrearranges the frames not chronologically arranged so that the framescan be chronologically obtained.

After being ready to obtain data from the original moving image dataframe by frame as the operation S2505, the signature device 205 obtainsa front frame (operation S2506). After obtaining it, the signaturedevice 205 shifts to a process of an operation S2507.

Then, see the flowchart depicted in FIG. 25B. The signature device 205runs a process for generating an independent frame for the obtainedframe (operation S2507). The process for generating an independent framewill be described later with reference to FIG. 26. After running theprocess for generating an independent frame, the signature device 205encodes the outputted independent frame into still image data (operationS2508). The signature device 205 specifically does JPEG encoding foreach of I-, P- and B-pictures to be encoded into JPEG image formats soas to generate still image data

After encoding the pictures, the signature device 205 extracts originalmetadata from the original moving image data (operation S2509), andencrypts the original metadata with a shared key of the signature device205 (operation S2510). Incidentally, a range to be encrypted is therange depicted in FIG. 12. After the encryption, the signature device205 writes the encoded still image data and the original metadata into anew still image data file to be generated (operation S2511).

Then, the signature device 205 generates digest data of the still imagedata file (operation S2512). After generating the digest data, thesignature device 205 decides whether the obtained frame is a last frame(operation S2513). If there is a successive frame (operation S2513: No),the signature device 205 obtains a next frame (operation S2514) andshifts to the process of the operation S2507.

If the obtained frame is a last frame (operation S2513: Yes), thesignature device 205 generates digest data for the entire originalmoving image data (operation S2515). After generating the digest data,the signature device 205 runs a process for generating an electronicsignature of the signature device 205 for the original moving image dataand a collection of digest data of all still image data files (operationS2516), and finishes the process for generating a signature to be put tothe original moving image data.

FIG. 26 is a flowchart which depicts a process for generating anindependent frame. The signature device 205 checks whether an obtainedframe is an I-picture (operation S2601). The I-picture mentioned hereincludes an IDR-picture.

If it is an I-picture (operation S2601: Yes), the signature device 205converts the obtained frame into an independent frame (operation S2607).If the obtained frame is a P- or B-picture (operation S2601: No), thesignature device 205 obtains a frame which is a preceding I- orP-picture (operation S2602). The term preceding means a directiontowards the past on a time axis.

Then, the signature device 205 checks whether the obtained frame is aP-picture (operation S2603). If the obtained frame is a P-picture(operation S2603: Yes), the signature device 205 converts the precedingframe and the obtained frame into an independent frame (operationS2606). If the obtained frame is a B-picture (operation S2603: No), thesignature device 205 obtains a frame which is a succeeding I- orP-picture (operation S2604). After obtaining it, the signature device205 converts the preceding frame, the succeeding frame and the obtainedframe into an independent frame (operation S2605).

After processing the operation S2607, S2606 or S2605, the signaturedevice 205 outputs the independent frame (operation S2608) and finishesthe process. Incidentally, a specific example of the conversion of theoperation S2607, S2606 or S2605 is the process going on from what isindicated by the reference numeral 903 to what is indicated by thereference numeral 904 as earlier described with reference to FIG. 9.

FIGS. 27A, 27B, 27C and 27D form a flowchart which depicts an exemplaryprocess for generating a cut off still image data file. See theflowchart depicted in FIG. 27A. The playback/extraction terminal 203sends a request to the signature device 205 for login of an extractor(operation S2701). After sending the request for login, theplayback/extraction terminal 203 waits for a reply to come from thesignature device 205.

Upon receiving the request for login from the playback/extractionterminal 203, the signature device 205 certifies the extractor whosedata is in the user data (operation S2702). A specific method forcertifying the extractor as the operation S2702 is as follows. If theextractor user data list 1002 includes a record which agrees with thereceived user data, the signature device 205 certifies the extractor whorequested to log in as the right extractor.

After certifying the extractor, the signature device 205 decides whetherthe certification resultantly indicates the right extractor (operationS2703). If the right extractor is indicated (operation S2703: Yes), thesignature device 205 sends the original moving image data registrationlist 1301 to the playback/extraction terminal 203 (operation S2704).Unless the right extractor is indicated (operation S2703: No), thesignature device 205 notifies the playback/extraction terminal 203 of anerror (operation S2705) and finishes the process for generating a cutoff still image data file.

Upon receiving what is sent from the signature device 205, theplayback/extraction terminal 203 decides whether what is received fromthe signature device 205 is the original moving image data registrationlist 1301 (operation S2706). If it is the original moving image dataregistration list 1301 (operation S2706: Yes), the playback/extractionterminal 203 displays the original moving image data registration list1301 (operation S2707), and accepts a choice of original moving imagedata to be extracted (operation S2708). After the extractor's choice,the playback/extraction terminal 203 sends a request to the signaturedevice 205 for a process for cutting off the chosen moving image data(operation S2709) and waits for a reply to come from the signaturedevice 205.

Unless what is received is the original moving image data registrationlist 1301 (operation S2706: No), the playback/extraction terminal 203displays an error notice (operation S2710) and finishes the process forgenerating a cut off still image data file. Further, the signaturedevice 205 receives a request for a cut off process (operation S2711)and shifts to a process of an operation S2712.

Then, see the flowchart depicted in FIG. 27B. The signature device 205brings out the original moving image data and signature data to beextracted filed in the moving image management DB 500 a (operationS2712) and runs a process for verifying signature data of the originalmoving image data (operation S2713). After running that process, thesignature device 205 decides whether a result of the verification provessuccessful (operation S2714). If it proves successful (operation S2714:Yes), the signature device 205 sends instructions to continue the cutoff process to the playback/extraction terminal 203 (operation S2715).If it proves unsuccessful (operation S2714: No), the signature device205 notifies the playback/extraction terminal 203 of an error (operationS2716).

Upon receiving what is sent from the signature device 205, theplayback/extraction terminal 203 decides whether the instructions tocontinue the cut off process are received (operation S2717). Uponreceiving the instructions to continue the cut off process (operationS2717: Yes), the playback/extraction terminal 203 accepts an appointedcut off location (operation S2718). After the extractor appoints the cutoff location, the playback/extraction terminal 203 sends cut offlocation data to the signature device 205 (operation S2719).Incidentally, the playback/extraction terminal 203 waits for a reply tocome from the signature device 205 after sending the cut off locationdata. Unless the instructions to continue the cut off process arereceived (operation S2717: No), the playback/extraction terminal 203displays an error notice (operation S2720) and finishes the process forgenerating a cut off still image data file. Further, the signaturedevice 205 receives the cut off location data (operation S2721) andshifts to a process of an operation S2722.

Then, see the flowchart depicted in FIG. 27C. The signature device 205runs a process for generating an independent frame of a frame on the cutoff location (operation S2722). After running that, the signature device205 encodes the outputted independent frame into still image data(operation S2723). After encoding that, the signature device 205extracts original metadata corresponding to the cut off location fromthe original moving image data (operation S2724), and encrypts theoriginal metadata corresponding to the cut off location with the sharedkey of the signature device 205 (operation S2725). After encryptingthat, the signature device 205 writes the still image data and theoriginal metadata into a file to be the cut off still image data file(operation S2726).

After writing that, the signature device 205 obtains cut off time andshelters it into the storage area (operation S2727). Then, the signaturedevice 205 obtains the extractor ID and shelters it into the storagearea (operation S2728). The signature device 205 generates cut offmetadata from the obtained cut off time and extractor ID (operationS2729) and shifts to a process of an operation S2730.

Finally, see the flowchart depicted in FIG. 27D. The signature device205 encrypts the cut off metadata with the shared key of the signaturedevice 205 (operation S2730) and generates digest data of the cut offstill image data file (operation S2731). Incidentally, the digest datagenerated by the operation S2731 is generated for a combination of thecut off still image data file and the peculiar data of the signaturedevice 205. Further, a range in which the digest data is generated bythe operation S2731 may be the entire cut off still image data filewhich is the digest range 1 as described with reference to FIG. 15.Further, the range in which the digest data is generated may be theoriginal image data ID through extractor ID fields which is the digestrange 2.

After generating that, the signature device 205 writes the cut offmetadata into the still image data file (operation S2732) and files itinto the moving image management DB 500 a as a cut off still image datafile (operation S2733). After filing that, the signature device 205sends the cut off still image data file to the playback/extractionterminal 203 (operation S2734) and finishes the process for generatingthe cut off still image data file.

The playback/extraction terminal 203 receives the cut off still imagedata file (operation S2735), stores the received cut off still imagedata file (operation S2736) and finishes the process for generating thecut off still image data file.

As described above, the signature device 205 entirely takes charge ofthe cut off processing function so that the playback/extraction terminal203 just accepts instructions about a location of extraction, and thatthe cut off process can be run while no encryption key kept by thesignature device 205 is taken into account.

FIG. 28 is a flowchart which depicts an exemplary process for verifyingsignature data of original moving image data. The signature device 205runs a process for verifying signature data of original moving imagedata (operation S2801). After running the process, the signature device205 decides whether the verification resultantly proves successful(operation S2802). If the verification resultantly proves successful(operation S2802: Yes), the signature device 205 generates digest datafor the entire original moving image data (operation S2803). Aftergenerating that, the signature device 205 compares the generated digestdata with the digest data for the entire original moving image datafiled in the signature data (operation S2804). After comparing them, thesignature device 205 decides whether the comparison resultantly provesthat the both digest data agree with each other (operation S2805).

If the comparison resultantly proves that the both digest data agreewith each other (operation S2805: Yes), the signature device 205 outputsa result of the verification as being successful (operation S2806) andfinishes the process for verifying the signature data of the originalmoving image data. Unless the verification resultantly proves successful(operation S2802: No) or unless the comparison resultantly proves thatthe both digest data agree with each other (operation S2805: No), thesignature device 205 outputs a result of the verification as beingunsuccessful (operation S2807) and finishes the process for verifyingthe signature data of the original moving image data.

FIGS. 29A and 29B form a flowchart which depicts an exemplary processfor verifying a cut off still image data file. To begin with, see theflowchart depicted in FIG. 29A. The playback/extraction terminal 203brings out a cut off still image data file (operation S2901). Afterbringing out that, the playback/extraction terminal 203 sends the cutoff still image data file having been brought out to the verificationterminal 204 (operation S2902) and finishes the process for verifyingthe cut off still image data file.

The verification terminal 204 receives the cut off still image data file(operation S2903) and sends a request to the signature device 205 forlogin of a verifier (operation S2904). After sending that, theverification terminal 204 waits for a reply to come from the signaturedevice 205.

Upon receiving the request for login from the verification terminal 204,the signature device 205 certifies the verifier whose data is in theuser data (operation S2905). A specific method for certifying theverifier as the operation 2905 is as follows. If the verifier user datalist 1003 includes a record which agrees with the received user data,the signature device 205 certifies the verifier who requested to log inas the right verifier.

After certifying the verifier, the signature device 205 decides whetherthe certification indicates the right verifier (operation S2906). If theright verifier is indicated (operation S2906: Yes), the signature device205 extracts original metadata and cut off metadata from the cut offstill image data file (operation S2907). A specific method forextracting that is as follows. If the cut off still image data file isin a JPEG format, the signature device 205 detects a marker in the cutoff still image data file.

If the type of the detected marker is “0xFFE1” which indicates APP1, thesignature device 205 extracts original metadata up to a data patternindicated by the successive data length field. Further, if the type ofthe detected marker is “0xFFE2” which indicates APP2, the signaturedevice 205 extracts cut off original metadata up to the data patternindicated by the successive data length field. Further, in case ofanother marker, the signature device 205 skips the data patternindicated by the successive data length field and detects a next marker.

After extracting the original metadata and the cut off metadata, thesignature device 205 decodes encrypted fields in the original metadataand the cut off metadata with the shared key of the signature device 205(operation S2908). After decoding them, the signature device 205searches the original moving image data and the signature data filed inthe moving image management DB 500 a with respect to the original movingimage data ID field in the original metadata (operation S2909) and runsa process for verifying the signature data of the original moving imagedata (operation S2910). After running that process, the signature device205 decides whether a result of the verification proves successful(operation S2911). If it proves successful (operation S2911: Yes), thesignature device 205 shifts to a process of an operation S2913.

Unless the right verifier is indicated (operation S2906: No) or unlessthe verification proves successful (operation S2911: No), the signaturedevice 205 notifies the verification terminal 204 of an error (operationS2912) and finishes the process for verifying the cut off still imagedata file.

Then, see the flowchart depicted in FIG. 29B. The signature device 205generates digest data of the cut off still image data file excluding thecut off metadata (operation S2913). After generating that, the signaturedevice 205 searches the digest data in the signature data with respectto a value in the frame number field in the original metadata (operationS2914).

After searching that, the signature device 205 compares the generateddigest data with digest data having been searched for and found out(operation S2915). After comparing the both digest data, the signaturedevice 205 decides whether the comparison resultantly proves that theboth digest data agree with each other (operation S2916). If thecomparison resultantly proves that the both digest data agree with eachother (operation S2916: Yes), the signature device 205 generates digestdata of the cut off still image data file (operation S2917).Incidentally, the digest data generated by the operation S2917 isgenerated by means of data in which data such that the cut off stillimage data file includes the peculiar data of the signature device 205is included.

After generating that, the signature device 205 compares the generateddigest data with the digest data of the cut off still image data file inthe cut off metadata (operation S2918). After comparing the both digestdata, the signature device 205 decides whether the comparisonresultantly proves that the both digest data agree with each other(operation S2919). If the comparison resultantly proves that the bothdigest data agree with each other (operation S2919: Yes), the signaturedevice 205 sends a result of the verification to the verificationterminal 204 (operation S2920) and finishes the process for verifyingthe cut off still image data file. Unless the comparison resultantlyproves that the both digest data agree with each other (operation S2919:No), the signature device 205 notifies the verification terminal 204 ofan error (operation S2921) and finishes the process for verifying thecut off still image data file.

Upon receiving what is sent from the signature device 205, theverification terminal 204 decides whether what is received is a resultof the verification of the cut off still image data file (operationS2922). Upon receiving a result of the verification of the cut off stillimage data file (operation S2922: Yes), the verification terminal 204displays the result of the verification of the cut off still image datafile (operation S2923) and finishes the process for verifying the cutoff still image data file. Upon receiving no result of the verificationof the cut off still image data file (operation S2922: No), theverification terminal 204 displays an error notice (operation S2924) andfinishes the process for verifying the cut off still image data file.

According to the signature device, the method for signature and theprogram for signature described above, write original metadata foridentifying image data into image data generated from moving image dataso as to put a signature to the image data. The signature device canthereby generate image data which facilitates identification ofsignature data to be related to confirmation of the original. As theoriginal metadata is included in an object to be signed, the signaturedevice can detect an alteration if any and can easily identify thesignature data by using a key for searching the moving image data andthe signature data included in the original metadata in condition of noalteration.

Further, since a signature device has to have a plurality of tables formanaging moving image data and signature data together, an existingsignature device suffers from increased operation cost and a huge amountof data. The signature device of the embodiment does not have to managemoving image data and signature data together as data to be used forsearching the signature data is included in the image data to be opened,and can thereby reduce the operation cost. Further, the ordinarily knownsignature device takes time for searching a huge amount of data. Thesignature device of the embodiment can reduce an amount of data to beheld, though, and can reduce time for searching the data.

Further, the signature device may write cut off metadata to be data intime of a cut off operation into a cut off still image data file, so asto generate digest data for the cut off still image data file includingthe cut off metadata. The signature device can thereby keep the data intime of the cut off operation unaltered.

Further, the signature device may generate digest data for a combinationof the cut off still image data file that the cut off metadata iswritten into and peculiar data of the signature device, and include thedigest data in the cut off still image data file. The signature devicethereby does not have to store in itself the digest data of the cut offstill image data file including the cut off metadata, and can reduce theamount of data in the signature device.

Further, the signature device may generate digest data for a combinationof original metadata of the cut off still image data file, the cut offmetadata and peculiar data of the signature device, and include thedigest data in the cut off still image data file. The signature devicecan thereby reduce time for generation of the digest data which protectsthe cut off still image data file from alteration, and can reduce timefor signature generation and signature verification.

Further, the signature device may decide in a group of stored summarydata whether summary data such that a combination of moving image dataand location data of image data in the moving image data corresponds todata extracted from image data to be verified agrees with summary dataof the image data to be verified. The signature device can therebyeasily identify corresponding summary data from a huge group of summarydata by using original metadata written into the image data to beverified.

Further, the moving image data stored in the signature device may becompressed moving image data. Further, the compressed moving image datamay be inter-frame compressed moving images. Further, data made open tothe public is a still image data file according to the embodiment, andmay be moving image data which is part of moving image data instead. Thesignature device may cut off moving image data from original movingimage data, e.g., on a GOP-by-GOP basis, and may write cut off metadatainto the cut off moving image data so as to open it to the public.

Incidentally, run a program for signature prepared in advance on acomputer such as a personal computer or a workstation so that the methodfor signature explained according to the embodiment can be implemented.The program for signature is recorded on a computer-readable recordingmedium such as a hard disk, a flexible disk, a CD-ROM, an MO or a DVD,and is read from the recording medium by the computer so as to be run.Further, the program for signature may be distributed through a networksuch as the Internet.

All examples and conditional language recited herein are intended forpedagogical purposes to aid the reader in understanding the inventionand the concepts contributed by the inventor to furthering the art, andare to be construed as being without limitation to such specificallyrecited examples and conditions, nor does the organization of suchexamples in the specification relate to a showing of the superiority andinferiority of the invention. Although the embodiment of the presentinvention has been described in detail, it should be understood that thevarious changes, substitutions, and alterations could be made heretowithout departing from the spirit and scope of the invention.

1. A signature device comprising: a storage unit configured to storemoving image data; and a processor configured to extract originalmetadata from moving image data for the image data of each of aplurality of images forming the moving image data, the original metadataincluding location data of the image data and identification data of themoving image data, to encode the image data of each of the images intostill image data in accordance with an image format, to write the stillimage data into a first area, to write the original metadata extractedby the extractor into a second area, the first area and the second areabeing included in a storage area of a still image data file in which thestill image data is filed, and to generate summary data for the stillimage data file.
 2. The signature device according to the claim 1,wherein the processor is further configured to specify image datalocation data on the basis of location data of image data of one of theplural images specified by a user to whom identification data is set, togenerate cut off metadata including time when the location data isspecified, the cut off metadata including identification data of theuser who has specified the location data, to write the cut off metadatainto a third area in the still image data file, and to generate summarydata for the still image data file.
 3. The signature device according tothe claim 2, wherein the processor is further configured to generate newsummary data for a combination of the still image data file and peculiardata of the signature device, and to write the new summary data into afourth are in the still image data file.
 4. The signature deviceaccording to the claim 2, wherein the processor is further configured togenerate new summary data for a combination of original metadata of theimage data of one of the plural images, the cut off metadata andpeculiar data of the signature device, and to write the new summary datainto a fourth are in the still image data file.
 5. A signature devicecomprising: a storage unit configured to store moving image data, thestorage unit being configured to store respective summary data of astill image data file in relation to location data of each of aplurality of images in the moving image data, the still image data fileincluding a first area and a second area, the first area being an areain which still image data encoded from image data in accordance with animage format is stored, the second area being an area in which data oflocation of the image data in the moving image data and identificationdata of the moving image data are stored; and a processor configured toextract data filed in the second area in the still image data file to beverified; to search a group of summary data stored in the storage unitfor summary data such that a combination of the identification data ofthe moving image data and the location data of the image datacorresponds to the data extracted; to generate summary data for thestill image data file to be verified; to make a decision whether thesummary data searched for agrees with the summary data generated; and tooutput the decision to display.
 6. A signature method comprising:extracting original metadata from moving image data for image data ofeach of a plurality of images forming the moving image data, theoriginal metadata including location data of the image data andidentification data of the moving image data; encoding the image data ofeach of the images into still image data in accordance with an imageformat; writing the still image data into a first area; writing theoriginal metadata extracted by the extractor into a second area, thefirst area and the second area being included in a storage area of astill image data file in which the still image data is filed; andgenerating summary data for the still image data file.